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Cornell University and Jefferson Laboratory physicists have been studying the properties of a new type of synchrotron radiation machine, called and Energy Recovery Linac (ERL), based on a superconducting linac and a one-turn return arc (like a storage ring).  A 5 to 7 GeV, 10 to 200 mA ERL machine could produce electron beams of a few microns diameter with very low emittances (8 to 100 pm) in both the horizontal and the vertical planes.  Small gap undulators up to 25 meters in length can produce ultra-high brilliance x-ray beams with many desirable characteristics, including: transversely coherent, diffraction-limited hard x-rays of very short (~20 fs to 2 ps), frequent (1.3GHz) pulses, with no limits on beam lifetime and very flexible modes of operation.  This combination of characteristics opens new possibilities and could significantly advance the state of the art in x-ray research.

Additional information about ERL and other Cornell accelerator physics may be found at


NSF awards Cornell $18 million to develop a new source of X-rays
ITHACA, N.Y. -- The National Science Foundation (NSF) has awarded Cornell University $18 million to begin development of a new, advanced synchrotron radiation x-ray source, called an Energy Recovery Linac (ERL). The ERL, based on accelerator physics and superconducting microwave technology in which Cornell's Laboratory of Elementary Particle Physics (LEPP) is a world leader, will enable investigations of matter that are impossible to perform with existing X-ray sources.  Click here for complete article. 
Published in the Cornell Chronicle Volume 36 Number 23, February 24, 2005.  Click here for Cornell News February 21, 2005 Press Release.


Graphic by: "Review of Third and Next Generation
Synchrotron Light Sources
" by Donald H. Bilderback,
Pascal Elleaume and Edgar Weckert,
J. Phys. B: At. Mol. Opt. Phys. 38 (2005) S773-S797


Schematic diagram of an Energy Recovery Linac source of synchrotron radiation.  A bright electron source injects electrons at up to a 1.3 GHz rate into a superconducting radio frequency (RF) cavity that accelerates electrons to full energy of 5 GeV (the green balls "surfing" on the crest of the RF traveling wave).  They circulate around a return arc producing brilliant x-ray beams in undulators (shown in red rectangles).  The circumference of the arc is adjusted so that the path length of the electrons returning to the linac is 180 degrees out of accelerating phase.  Thus these (red ball) electrons ride in the trough of the RF wave and now give up their energy to the cavity.  After being decelerated to low energy they are directed to a beam dump.  Each electron makes one trip around the arc and its energy is recycled in the main linac, hence the name, Energy Recovery Linac.  We plan to adapt this schematic concept to the real physical layout of the current CESR storage ring by the addition of further underground tunnel to be connected to the present storage ring complex.  The details are being worked out now and an upgrade plan will be presented to the NSF a few years from now.


NSF Approves New C.U. X-Ray System
The National Science Foundation has given Cornell the green light to begin development of an Energy Recovery Linac (ERL), a new advanced synchrotron radiation X-ray source that has far-reaching implications for biology, chemistry and a host of other disciplines.  The proposed ERL will feed into the Cornell Electron Storage Ring (CESR) underneath Alumni Field but will produce X-rays with greater capabilities than the University's current synchrotron radiations source can provide.  Click here for complete article.  Published in the Cornell Daily Sun Volume 121 Number 100, March 2, 2005.


$109 million NSF award funds X-ray science, research and development for revolutionary new X-ray source
In a major boost for X-ray science and accelerator physics, the National Science Foundation (NSF) has committed about $109 million to Cornell's continued operation of an X-ray synchrotron facility, as well as to develop a new kind of X-ray source that promises to revolutionize the field.  Click here for complete article.